DEBT - Summary of Mortgage Warehouse Borrowings (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Line of Credit Facility [Line Items]
Amount Drawn	$ 200,662	$ 413,887
Secured Debt
Line of Credit Facility [Line Items]
Amount Drawn	200,662	413,887
Facility Amount	410,000	760,000
Mortgage borrowings outstanding, collateralized amount	229,700	467,500
Collateralized amount of restricted short-term investments	1,600	3,500
Secured Debt | Warehouse A
Line of Credit Facility [Line Items]
Amount Drawn	2,553	12
Facility Amount	$ 10,000	$ 10,000
Secured Debt | Warehouse A | LIBOR
Line of Credit Facility [Line Items]
Interest Rate	1.75%	1.75%
Secured Debt | Warehouse B
Line of Credit Facility [Line Items]
Amount Drawn	$ 21,618	$ 86,409
Facility Amount	$ 75,000	$ 150,000
Secured Debt | Warehouse B | LIBOR
Line of Credit Facility [Line Items]
Interest Rate	1.75%	1.75%
Secured Debt | Warehouse C
Line of Credit Facility [Line Items]
Amount Drawn	$ 69,898	$ 116,601
Facility Amount	$ 125,000	$ 250,000
Secured Debt | Warehouse C | LIBOR
Line of Credit Facility [Line Items]
Interest Rate	2.05%	2.05%
Warehouse D | Secured Debt
Line of Credit Facility [Line Items]
Amount Drawn	$ 30,556	$ 105,065
Facility Amount	$ 100,000	$ 150,000
Warehouse D | Secured Debt | LIBOR
Line of Credit Facility [Line Items]
Interest Rate	1.65%	1.65%
Warehouse E | Secured Debt
Line of Credit Facility [Line Items]
Amount Drawn	$ 76,037	$ 105,800
Facility Amount	$ 100,000	$ 200,000
Warehouse E | Secured Debt | LIBOR
Line of Credit Facility [Line Items]
Interest Rate	1.50%	1.50%